There are two type of Health and Mana "potions" in Runes of Magic: Regeneration over Time and Instant Regeneration.

Regeneration over Time potions include: Simple Magic Potion, First Aid Potion, Major Magic Potion, Elemental Mana Stone and Barbarian Herbs. Although they seem very different (on the surface) the game regards them as the same. They each will regenerate a fixed amount of Health or Mana instantly, plus an additional smaller burst every few seconds for a fixed duration. These can be excellent to use early in a fight so you get continued small heals over time while you conitnue to take damage or use mana.

The second type, Instant Regeneration, is just that. They heal a large fixed amount of Health or Mana instantly, with no continued effect.

Now here is the important thing to remember... they use different timers! You can use an Instant Health potion and an Over Time Mana potion at the same time. They do not conflict!

Other Potions

There are a few "Other Purpose" potions in the game, such as Savage Power, that do special things but most of these are quest items, given to by or for a quest and intended to be used to help you complete that quest.